Flow passage coupling unit

Abstract

A flow passage coupling unit (1) for flow passages (2, 4) of movable and fixed members (3, 5), which includes a cylindrical body (6) secured to the movable member and having a large bore (10) communicating with the flow passage, a small bore (11) and a value seat (12) formed between the large and small bores; a sliding valve (7) having a cylindrical sliding surface (7a) which slidably fits in the small bore and has an axial passage (14), a valve head (17) movable within the large bore, and a through-hole (16) provided through the cylindrical sliding surface adjacent the valve head; a coil spring (13) provided within the large bore for biasing the valve head against the valve seat so that communication between the large bore and the axial passage is normally cut off; and the valve seat (12) made in a plane which is perpendicular to an axis of the sliding valve.

We claim: 
     
       1. A flow passage coupling unit for coupling a first passage of a first member and a second passage of a second member, which comprises: a body secured to said first member and having a large bore communicating with said first passage, a small bore terminating at a coupling opening, and a valve seat formed at a shoulder portion between said large and small bores;   a sliding valve having a cylindrical sliding surface which slidably fits in said small bore and has an axial passage terminating at a coupling opening, a valve head integral with said cylindrical sliding surface and movable within said large bore, and a through-hole provided through said cylindrical sliding surface adjacent said valve head, said sliding valve having a front end opposite to said valve head projecting from a front end of said cylindrical body by a predetermined distance at a time of non-connection;   spring means provided within said large bore for biasing said valve head against said valve seat so that communication between said large bore and said axial passage is normally cut off;   an abutment surface of said valve head made in a plane which is perpendicular to an axis of said sliding valve; and   said sliding valve is provided with a circumferential groove on a sliding surface thereof over said through-hole, whereby a distance traveled by said sliding valve to provide a desired area of opening space between said valve head and said valve seat is minimized.   
     
     
       2. The flow passage coupling unit of claim 1, wherein said circumferential groove has a width greater than a diameter of said through-hole. 
     
     
       3. The flow passage coupling unit of claim 1, wherein said flow passage coupling unit is characterized in that (1) the cross area of said axial passage is not greater than four times the cross area of said through-hole; (2) the maximum amount of lift is not less than twice the depth of said circumferential groove; (3) the width of said circumferential width is not less than the diameter of said through-hole; and that (4) the minimum opening between said through-hole and said valve seat is equal to the minimum area necessary for flows into said axial passage from said circumferential groove via said through hole. 
     
     
       4. The flow passage coupling unit of claim 3, wherein the depth of said circumferential groove is determined based on said minimum area. 
     
     
       5. A flow passage coupling unit for coupling a first passage of a first member and a second passage of a second member, which comprises: a body secured to said first member and having a large bore communicating with said first passage, a small bore terminating at a coupling opening, and a valve seat formed at a shoulder portion between said large and small bores;   a sliding valve having a cylindrical sliding surface which slidably fits in said small bore and has an axial passage terminating at a coupling opening, a valve head integral with said cylindrical sliding surface and movable within said large bore, and a through-hole provided through said cylindrical sliding surface adjacent said valve head, said sliding valve having a front end opposite to said valve head projecting from a front end of said body by a distance necessary for connection when said sliding valve is not connected;   spring means provided within said large bore for biasing said valve head against said valve seat so that communication between said large bore and said axial passage is normally cut off;   an abutment surface of said valve head made in a plane which is perpendicular to an axis of said sliding valve so that a distance traveled by said sliding valve to provide a desired area of opening space between said valve head and said valve seat is minimized; of said coupling opening; and   a coupling surface provided on said second member around said second passage so as to oppose to said sliding valve so that said sealing member and coupling surface cooperate to keep airtight a coupling between said first and second passage through said large bore and said axial passage.   
     
     
       6. The flow passage coupling unit of claim 5, wherein said sealing member is an O-ring having a diameter smaller than that of said sliding surface so that said sliding valve is pressed against said coupling surface by a large force.